# The sexual-desire experiments

> Sexual desire in the kisspeptin trials — Real TRT — Real TRT looks closely at kisspeptin's male sexual-desire trial, attraction-related brain imaging and a human anxiety result that deserves separate attention.

**Sexual desire & the brain**

The most interesting observations here give desire its own measurements.

## The trial in 32 men

The [randomized trial in 32 men with hypoactive sexual desire disorder](https://pubmed.ncbi.nlm.nih.gov/36735255/) examined intravenous kisspeptin-54 against placebo in a double-blind crossover design. Each participant experienced both conditions, allowing the comparison to run within the same people. The researchers measured sexual-processing brain activity, penile tumescence and self-reported desire. Tumescence means the physical swelling associated with an erection; it gives the experiment a bodily measurement alongside the reports and imaging.

The study found modulation of sexual-processing brain networks, increased penile tumescence by up to 56% over placebo, and heightened self-reported sexual desire. No adverse events were reported in that trial. The phrase up to matters: it describes the reported extent of that measured effect and cannot stand for an average improvement in desire.

I'm more impressed by the combination of measurements than by the largest percentage. It gives the experiment several ways to register a response. Brain activity, physical arousal and reported desire can each contribute information without being squeezed into a single claim about testosterone.

## Attraction during brain imaging

A [human functional-neuroimaging study](https://pubmed.ncbi.nlm.nih.gov/32051344/) examined responses to visual and olfactory cues of attraction. Kisspeptin enhanced activity in olfactory and limbic regions involved in sexual behaviour, with the largest effects in men reporting lower sexual quality of life. The particular task matters: this was a response to specified cues during an experiment.

Testosterone initially looked like the main subject to me. My curiosity moved toward the connection between a reproductive signal and the brain's processing of attraction. These experiments ask something richer than whether a blood concentration changes, even though the result still needs to be understood within its testing conditions.

The scanner image can look unusually authoritative. It is easy to mistake the apparent precision of a brain image for completeness. The finding interests me because of the task, the comparison and the accompanying human outcomes. An image alone would leave too much of the argument unfinished.

The desire work has earned my enthusiasm. A sustained improvement people value in their lives would take the argument further. That would require follow-up built around those experiences, alongside the physiological observations. A larger response to a cue would leave that question open.

The [2025 review of possible treatment for sexual dysfunction](https://pubmed.ncbi.nlm.nih.gov/40189467/) discusses kisspeptin's effects on sexual and emotional processing, along with its potential and current limitations. It is a useful place to situate the experiments without projecting a finished treatment onto them.

The next study that follows those experiences would deserve a careful afternoon. The [reading list](/references) has the papers discussed here; the [repeated-exposure findings](/repeated-signal) explain why an appealing initial effect makes me especially interested in what follows.

![Gouache illustration of an empty MRI scanner and a technician behind a control-room window](images/desire-scanner-room.webp)

*An imagined brain-imaging research room, illustrated in gouache; it does not depict the location or participants of either study.*

## The anxiety result

The [2025 randomized crossover anxiety trial](https://pubmed.ncbi.nlm.nih.gov/40036336/) involved 95 participants, comprising 63 men and 32 women. Kisspeptin-54 robustly increased LH, while state anxiety, cortisol, blood pressure and heart rate did not significantly change versus placebo. That combination is informative: the intervention had a measured hormonal effect, and the study did not detect the corresponding changes in those other endpoints.

I read that finding as a welcome constraint on the story. The desire experiments give reasons to pursue psychosexual effects; the anxiety experiment gives a specific result for a different question. A general mood-lift claim would flatten the distinction between them.

The absence of adverse events in the [male sexual-desire trial](https://pubmed.ncbi.nlm.nih.gov/36735255/) is encouraging within that experiment. I would still want safety assessed over the exposures and populations relevant to any proposed use. A well-observed session answers a narrower question than repeated exposure over a longer period.

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At Real TRT I scrutinise published research on kisspeptin and testosterone; this is an editorial site rather than a treatment business, and none of it is medical advice.